The invention concerns a longitudinal transfer system made out of rail sections for conducting transport cars from one work station to another, two adjacent rail sections being connected with one another mechanically and electrically.
As a result of the ever increasing demands of modern businesses in international competition, quality and quantity, and, in particular, productivity have to be increased in order for businesses to remain competitive. That is, the products have to be produced and assembled more cost-effectively. Correspondingly it is necessary that the production processes be automated and linked together. This linkage of production processes and assembly operations plays an ever increasing role in modern manufacturing.
In this case individual areas and processing stations in the plant are connected with one another and can cooperate with one another via longitudinal transfer systems.
A longitudinal transfer system essentially consists of individual rail tracks, which are assembled and on which workpieces to be processed or tools, in a given case are transported automatically on transport cars from work station to work station. Workpieces are processed at the work stations, then, for example, conveyed from the production area to the quality control area and then to the assembly area.
In order to overcome temporary bottlenecks and to make parallel assembly processes possible, for example, by-pass systems corresponding to EP-A 94102382.2 have been developed for a longitudinal transfer system. The by-pass system makes it possible to carry out parallel processes, which make highly flexible production processes possible.
Up to now it has not been possible to switch a longitudinal transfer system to another line within a short time. Only with considerable expenditure of time is it possible, for example, to integrate a by-pass into a longitudinal transfer system. This results in a breakdown of the entire transfer line and all other working processes are blocked. Therefore, for the most part these operations are performed on the weekend, and consequently they are extremely cost- and time-intensive.
A further significant disadvantage is that a longitudinal expansion (dilation) of the rail track of a longitudinal transfer system takes place as a result of temperature differences in the different, spatially separate production and assembly shops or as a result of seasonal changes. Therefore expansion joints, which of course have to be precisely bridged over, are provided between the individual rail tracks.
In this case also it is to be noted that the electric power of a longitudinal transfer system for corresponding cars, which convey workpieces and tools from one processing station to another, is conducted via the rail itself. Therefore current conductors, which consist of another material, such as the rail itself, are associated with the rails. This results in a different longitudinal expansion, which also has to be taken into account at the connecting points of the individual rail tracks.